The present invention relates to a transparent thermoplastic material containing 0.0001 to 2 wt. % of substantially planar metal identification platelets with a greatest longitudinal dimension of less than 200 μm and a thickness of 2-10 μm, a round or n-agonal shape where n≧4, characterised in that the metal identification platelets have no recesses or have recesses that lie substantially in the centre of the metal identification platelet, do not come closer than 20 μm to the circumferential outer edge of the metal identification platelet, and do not form more than 30% of the surface of the metal identification platelet, and also relates to its production and use for the preparation of films for personalising a card layer composite and card-shaped data carriers, in particular smart cards, magnetic strip cards, identity cards and the like.
Data carriers and in particular documents containing valuable information are as a rule provided with security features for protection purposes, which enable the validity of the data carrier to be checked and at the same time serve as protection against unauthorised copying of the data carrier. In many cases optically variable elements are used as security features, which enable the observer to check the validity of the document containing valuable information by various methods, for example by means of IR or UV spectroscopy as well as light microscopy.
Metal identification platelets can serve as a security feature and are in principle known and described for example in WO 2005/078530.
The use of such identification platelets is described for example in European Patent EP-A-1216758.
A microdot for the identification of products is known from UK Patent GB 2346583.